Task 1

16. Paragraph     ①     

17. Paragraph     ②     

18. Paragraph     ③     

19. Paragraph     ④     

20. Paragraph     ⑤     

A. Lightening Causes Puzzles to People

B. Types of Lightning

C. Causes of Lightning

D. Differences Between Thunder and Thunderstorm

E. Frequencies of Thunderstorms Occurring in the World and the U. S.

F. Shock Waves as Thunder

Compared with dreamless sleep, deep dream sleep is

• A、not the result of natural selection
  
  

• B、less likely to appear to monkeys
  
  

• C、more protective to the animals
  
  

• D、at a higher stage of evolution
  
  

The electric motors produced by Henry Manley's company are cheaper than those made in Japan.

• A、True
  
  

• B、False
  
  

• C、Not Given